Intelligent Model for Dynamic Shear Modulus and Damping Ratio of Undisturbed Marine Clay Based on Back-Propagation Neural Network

Abstract

In this study, a series of resonant-column experiments were conducted on marine clays from Bohai Bay and Hangzhou Bay, China. The characteristics of the dynamic shear modulus (G) and damping ratio (D) of these marine clays were examined. It was found that G and D not only vary with shear strain (γ), but they also have a strong connection with soil depth (H) (reflected by the mean effective confining pressure (σm) in the laboratory test conditions). With increasing H (σm) and fixed γ, the value of G gradually increases; conversely, the value of D gradually decreases, and this is accompanied by the weakening of the decay or growth rate. An intelligent model based on a back-propagation neural network (BPNN) was developed for the calculation of these parameters. Compared with existing function models, the proposed intelligent model avoids the forward propagation of data errors and the need for human intervention regarding the fitting parameters. The model can accurately predict the G and D characteristics of marine clays at different H (σm) and the corresponding γ. The prediction accuracy is universal and does not strictly depend on the number of neurons in the hidden layer of the neural network.

Assessment of small strain modulus in soil using advanced computational models

“…Neural networks with 3-3-1 and 3-2-1 architectures showed good performance in predicting the damping ratio( D ) and G of mica-sand mixtures 16 . When the Backpropagation Neural Net-work(BPNN) model was used to predict the G and D of marine clay 17 , the established model showed good predictive performance for marine clay at different strains and depths. In addition, a novel genetic expression programming model was used to predict the normalized shear modulus and damping ratio of sandy soils 18 .…”

Cyclic threshold shear strain for pore water pressure generation and stiffness degradation in marine clays at Yangtze estuary

“…earthquakes), they may suffer cyclic degradation, which will trigger stability problems of marine structures and reduce their service life. Hence the dynamic properties of marine clays under marine geology disasters have received extensive attention from the scientific and engineering communities (Fattah and Mustafa, 2016;Fattah et al, 2017;Yang et al, 2018;Zhu et al, 2020;Fattah et al, 2021;Pan et al, 2021;Jin et al, 2022;Lei et al, 2022;Tsai, 2022;Wu et al, 2023). The cyclic threshold shear strain for pore water pressure generation (g tp ) [when the cyclic shear strain amplitude (g c ) is below g tp , negligible pore water pressure generated, and while g c > g tp , pore water pressure accumulates significantly.]…”